172 ON THE CLASSIFICATION OF BIRDS. 
sea: they are always walking on its shores, or on 
sides of fresh waters; and they depend as much 
their. ambulations for seeking sustenance, as upon thei 
wings for those long expeditions they are known to make 
Their external structure varies considerably, particularl 
in regard to the number and disposition of their toes: the 
bill is generally long, and in the typical groups v 
slender ; the upper mandible is entire ; the wings pointed, 
and the tail invariably very short, the legs being use 
as a rudder during flight. : 
(194.) The families under which we consider the 
waders to be naturally arranged, are these: —-1. The 
ARDEAD#, or herons;—2. The CHaRaDRIADA, 
plovers ;— 3. The Trine1na, or sandpipers ;—4. The 
Rawuipé, or rails; —5. The TanrTauipa, or ibices. 
These seem, therefore, to follow the order in which we 
have placed the primary types of the animal kingdom: 
the second and the third are the typical groups, istine 
guished by having the hind toe either altogether wanting, 
or very short and elevated; while the three others, 
forming the aberrant dinietens have the hind toe of the 
usual proportionate length, and placed on the same level. 
with the others. Without attempting, in such a sketch 
as this, to point out the affinities by which these families 
may be connected, much less to expatiate upon the 
union of the different genera which have been arranged. 
under each, we shall merely add a few illustrations of 
their characters and habits to the scientific details sub- 
sequently given. ' 
(195.) The ArpEapa#, or herons, by means of the 
cranes, show the strongest affinity to the ostriches, and — 
thus unite the rasorial with the wading order. Nearly — 
all the cranes are large birds, with short and powerless 
wings; long, and frequently naked, necks ; and more ter- 
restrial in their habits than any of their congeners. The 
beautiful genus Phosphia, if truly belonging to this fa- 
mily, is more of a gallinaceous than a wading bird ; since — 
it lives in the forests of South America, and is sail v 
be sometimes domesticated for the purpose of guardi 
